Solder Powder 2017-06-15T21:35:26+00:00

Qualitek Solder Powder

Quality solder begins with quality powder and alloys. All Qualitek soldering alloys exceed J-STD-006 and ASTM B-32 Specifications

LEAD FREE ALLOY COMPOSITIONS
Alloy Composition
Melting Range
(°C)
Melting Range
(°F)
BAR
WIRE
PASTE/POWDER
SPHERE
Ecolloy TM
221-227
430-440
 
Sn100e TM
228
442
Bi58
Sn42/Bi58
139 E
282
 
Sn96.5
Sn96.5/Ag3.5
221 E
430
Sn95
Sn95/Ag5
221-245
430-473
LF217
Sn95.5/Ag4.0/Cu0.5
217-219
422-426
SAC 387
Sn95.5/Ag3.8/Cu0.7
217-219
422-426
SAC 357
Sn95.8/Ag3.5/Cu0.7
217-221
422-426
SAC 405
Sn95.5/Ag4.0/Cu0.5
217-221
422-426
SAC 305
Sn96.5/Ag3.0/Cu0.5
217-221
422-426
SAC 105
Sn98.5/Ag1.0/Cu0.5
217-228
422-442
   
 
Sn99
Sn99.3/Cu0.7
227 E
440
Sb5
Sn95/Sb5
232-240
450-464
xxE-Eutectic
xx*
US Patent 5, 435, 857
Above alloys subject to availability at time of inquiry and may require a minimum PO.  

 

STANDARD ALLOY COMPOSITIONS
Alloy Composition
Melting Range
(°C)
Melting Range
(°F)
BAR
WIRE
PASTE
SPHERE
Sn63/Pb37
183 E
361 E
Sn60/Pb40
183-190
361-374
Sn50/Pb50
183-214
361-420
   
Sn45/Pb55
183-225
361-440
   
Sn40/Pb60
183-238
361-460
 
Sn20/Pb80
183-280
361-536
   
Sn10/Pb90
268-302
514-576
 
Sn62/Pb36/Ag2
179-189
345-372
Sn10/Pb88/Ag2
268-299
514-570
xxE-Eutectic

Above alloys subject to availability at time of inquiry and may require a minimum PO.

                 

 

PARTICLE SIZE CHART TABLE 1
MESH SIZE MICRONS SIZE PARTICLE TYPE
-200+325 75-45 2
-325+500 45-25 3
-400+635 38-20 4
-500 25-15 5
-635 15-5 6

 

Qualitek Solder Powder
Solder powders are the key component of all solder pastes. Pastes made with the same flux but with powders that differ in particle sizes often have different rheological/physical properties resulting in differences in screen/stencil printing, component placement and production yields. The powder constituent of solder paste, in fact, affects all stages of surface mount assembly from stability and printability of the paste, to the quality of the final fillet.

Main Characteristics
Good solder powder must have the following properties: a “clean dry sand” appearance, a gray-silver color vs. a charcoal-gray, which indicates presence of oxidation and good flow behavior go to functional test. Other important features include high powder density close to the theoretical density of the alloy and no internal voids or external satellites (microspheres attached to a single sphere).

The trained eye of a technician often evaluates some of those properties. Others are governed by formal test procedures. For example, powder flow can be tested according to ASTM B-213, and the presence of voids can be checked by microscopic examination of cross section of individual particles. The user can identify the powder by both composition and type. Alloy composition refers to the main alloying elements; type to the range of particle (mesh) sizes.

Composition
Small variations in composition and the level of impurities can affect wetting properties of the solder paste: oxidation behavior, melting temperatures, flow within the joint and joint strength. The ideal solder composition will feature tight tolerances of alloy composition.

The J-STD-006 (Joint Industry Standard) places requirements on the content of alloying elements. For alloys with 5% of less of an element, its content must not vary by more tan 0.2% by weight. For elements contents higher than 5% the acceptable variation from the nominal is extended to 0.5%. Because of possible deleterious effects on the solder limits also are placed on the presence of 14 impurity elements. For instance, aluminum cadmium and arsenic impurities induce dewetting, and sulfur blamed for joint grittiness. However, even when the alloy’s composition is within the industry specification small variations in elemental content can affect joint aesthetics. One joint can turn out smooth and shimmy while another will display a dull an grainy appearance. To deal with these issues, paste manufacturers often impose in-house specifications that feature strict composition tolerances.

Powder Shape
Powder can be spherical or irregular. According to J-Std-006, powder is spherical if 90% of the particles have a length-to-width ratio of less that 1.5. For most applications a high degree of “sphericity” is preferred, the major advantage being lower surface area, which minimizes oxidation, and better load acceptance (less tendency for clogging and interlocking), which assists dispensability and release through the stencil aperture.

Particle roundness influences paste viscosity and the tendency to shear. Spheres offer less resistance to viscous flow compared with particles of irregular shape. Accordingly, paste made from the same flux and spherical powder will have lower viscosity than those of the same weight percent and particle size range but of irregular shape. One possible advantage with pastes of the latter appearance is that they are less likely to shear thin when screen/stencil printed at high speed and constant squeegee motion. Interlocking of the powder reduces paste flowout. Reduction of shear thinning is important because it will prevent slumping and smearing which can result in solder bridging and solder balling.

Powder Size
Powders are divided into six particle type with the finer powder represented by higher numbers. Table 1 also includes the customary designation of powders by mesh sizes of the sieves used to sort the particles according to ASTM B-214 Test Method 1.



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Qualitek Solder Powder

Quality solder begins with quality powder and alloys. All Qualitek soldering alloys exceed J-STD-006 and ASTM B-32 Specifications

LEAD FREE ALLOY COMPOSITIONS
Alloy Composition
Melting Range
(°C)
Melting Range
(°F)
BAR
WIRE
PASTE / POWDER
SPHERE
Ecolloy TM
221-227
430-440
Sn100e TM
228
442
Bi58
Sn42/Bi58
139 E
282
Sn96.5
Sn96.5/Ag3.5
221 E
430
Sn95
Sn95/Ag5
221-245
430-473
LF217
Sn95.5 / Ag4.0 / Cu0.5
217-219
422-426
SAC 387
Sn95.5 / Ag3.8 / Cu0.7
217-219
422-426
SAC 357
Sn95.8 / Ag3.5 / Cu0.7
217-221
422-426
SAC 405
Sn95.5 / Ag4.0 / Cu0.5
217-221
422-426
SAC 305
Sn96.5 / Ag3.0 / Cu0.5
217-221
422-426
SAC 105
Sn98.5 / Ag1.0 / Cu0.5
217-228
422-442
Sn99
Sn99.3 / Cu0.7
227 E
440
Sb5
Sn95 / Sb5
232-240
450-464
xxE-Eutectic
xx*US Patent 5, 435, 857
Above alloys subject to availability at time of inquiry and may require a minimum PO.
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